Nice article, but nothing really surprising when you follow the progression starting from 8080.

One correction though:

> EAX is called the “Accumulator register” is not just a convention, it actually makes a difference to the encoding (and potentially the performance, as a result)

No. As the decoder doesn't decode byte-by-bytes, but whole strings together and registers are all renamed meaning that %eax isn't really different from %ebx etc. the only difference is that it saves one byte of code space which is an extremely minor density improvement and you'd have to make a very contrived example to be able to measure the difference.